Phonograph reproducer with superaudible frequency



Patented May 8, 1934- PATENT OFFICE PHONOGRAPH REPRODUCER WITH SUPER-AUDIBLE FREQUENCY Julius Weinberger, New York, N. Y., assignor to RadioCorporation of America, a corporation of Delaware Application October27,

10 Claims.

The invention concerns a phonograph reproducer and has for its principalobject to provide a reproducer particularly adapted for playingphonograph records on which the markings correspond to super-audiblefrequency vibrations modulated at the frequencies of the sounds to bereproduced.

A further object of the invention is to provide a reproducer for suchmodulated high frequency records having a natural resonant frequencycorresponding to the frequency of the carrier wave or the high frequencyoscillations recorded on the record.

In a copending application, Ser. No. 60,369, filed Oct. 5, 1925, I havedisclosed and described a phonograph record on which the markingscorresponding to the sounds to be reproduced are in the nature ofengravings of super-audible frequency vibrations modulated at audiofrequencies. In making these records, a high frequency oscillator ofconstant frequency has its output modulated at audio frequencies and therecord is engraved by a stylus vibrated at these modulated highfrequencies. It is obvious that in playing such a record, if it isrotated at a constant speed, high frequency vibrations of constantfrequency will be imparted to the reproducing stylus.

I propose according to the present invention to provide a reproducerhaving a natural resonant frequency equal to that of the carrier orsuperaudible frequency used on the records. A reproducer made in thisway will naturally tend to vibrate at the carrier frequency and willeasily and readily follow the markings on the grooves. Such reproducersmay be made either of the piezo-electric crystal type using a crystalhaving the required natural frequency or electromagnetic orelectro-static reproducers whose vibrating elements have the requirednatural frequency.

The invention is illustrated by way of example in the accompanyingdrawing in which,

Fig. 1 shows a reproducer of the piezo-electric crystal type.

45: Fig. 2 shows a condenser reproducer. and

Figs. 3 and 4 show sectional views at right angles to each other of anelectro-magnetic reproducer. the section of Fig. 4 being taken along theline 44 of Fig. 3.

Figure 5 is an enlarged view of a portion of a record for which myimproved reproducer is especially adapted, and,

Figure 6 is a diagrammatic sketch of a turntable, record and reproducer.

Referring to Fig. 1 a piezo-electric crystal of 1925, Serial No. 65,135

the required frequency characteristics is shown at l and is fastened atits ends to two extended bases 4 and 5. The crystal is provided onopposite sides with sheets of insulating material 2 overlaying which area pair of metal plates 3 to which the connecting wires of the device maybe attached. The crystal with its base pieces is placed in a generallycylindrical container 7, the latter being provided at one end with aninternally extending flange 8 serving as an abutment to hold the basemember 5 in place. A resilient member 43 may be provided between theflange and the base member to permit vibrations of the latter. The basemember 4 rests against an annular shoulder in the opposite end of thecontainer 7 and is held in place by a cap 6 having screw threadedengagement with the container. A lever arm 9 pivoted at 10 on a lugintegral with the container 7, is fastened at one end to the centralportion of the base member 5 and is provided at its opposite end withthe stylus carrier 11. As the stylus follows the groove of the record itwill have vibrations impressed upon it of the natural frequency of thecrystal 1 and therefore in reproducing the record the crystal willvibrate at its natural frequency.

Fig. 2 shows a modification of the invention making use of a condenserreproducer. The plates of the condenser comprise the block 12 and thethin metallic diaphragm 13, of which the former is mounted on a block ofinsulation 4 and supported against an annular collar in the supportingring 15, being retained in place by the retaining ring 16. The diaphragm13 is clamped at its edges between co-acting annular serrations 20 inclamping rings 15. and 17 and these rings are fastened together bysuitable bolts 21. The thin diaphragm 13 naturally has a high naturalperiod of vibration and means are provided in the present case forstretching the diaphragm until its natural frequency corresponds to thatof the carrier wave on the record. In the present case, the stretchingmeans consists of a ring 18 bearing against the edge portion of thediaphragm between the annular support 117, forming part of the ring 17,and the clamp consisting of the serrations 20. The position of the ring18 can be adjusted by the screws 19 and by tightening or loosening thesescrews the proper tension can be applied to the diaphragm. The styluscarrier 24 is mounted on one end of a lever 22, pivoted at 23 and havingits opposite end secured to the middle portion of the diaphragm 13. Whenthe stylus vibrates in following the markings on the record,

the diaphragm 13 will be caused to vibrate at its natural frequency inwhich case the capacity of the condenser formed by the diaphragm andblocl: 12 will change in accordance with the vibrations.

An electro-magnetic type of reproducer is shown in Figs. 3 and 4. Thediaphragm 32 of this reproducer is clamped between serrations on thecasing 30 and the retaining ring 31 and means are provided for varyingthe tension on the diaphragm, consisting of the ring 40 adjustable as toposition by means of the adjusting screws il. This arrangement isentirely similar to that shown in Fig. 2. Within the casing 30 isprovided a U-shaped magnet 36 having extensicns 37 fastened to its endswhich extensions are provided with pole pieces 38, the end of these polepieces being located in proximity to the center of the diaphragm. Theoperating coils 39 are wound on the extending pole pieces 38. It will beunderstood that in this case also, the diaphragm 32 will be properlytensioned to cause it to have a natural resonant frequency equal to thecarrier wave frequency of the records to be reproduced; The lever 33 ispivoted at 35 and attached at one end to the center of the diaphragm 32.At its other end it carries the stylus carrier 34. As the diaphragmvibrates in response to the movements of the stylus, it will vary theair gap between the magnetic pole pieces 38 and cause a variation in theflux through the pole pieces corresponding to the vibrations of thediaphragm. This varying flux induces currents in the coils 39 whichlikewise correspond in frequency and amplitude to the original markingson the phonograph record.

Figure 5 is an enlarged view of a portion of a record 101 upon whichmodulated waves 151 have been engraved.

Figure 6 shows diagrammatically such a record upon a turn-table 103 inposition for playing, I02 representing a reproducer which may be any oneof the types shown in Figures 1 to 4.

While I have illustrated and described my invention with respect toseveral specific modifications, it will be obvious that various otheradaptations will readily suggest themselves to those skilled in the art;for example, the vibrating elements of the condenser and magneticreproducers need not be diaphragms but can be other elements having therequisite frequency characteristics.

I intend to be limited therefore only as indicated by th scope of thefollowing claims:

1. A phonograph reproducer for reproducing phonograph records havingmodulated high frequency vibrations recorded thereon comprising anelement adapted to be vibrated by said recorded vibrations, said elementhaving a natural resonant frequency equal to the carrier wave frequencyrecorded on the record.

2. A phonograph reproducer for reproducing phonograph records havingmodulated high frequency vibrations recorded thereon comprising apiezo-electric crystal having a mechanical resonant frequency equal tothe carrier wave frequency recorded on the record.

3. In combination, a record having a modulated wave engraved thereon,and a reproducer having an element whose natural period of oscillationis substantially equal to the period of the engraved wave.

4. In combination, a record having a wave of constant frequencymodulated by a variable frequency recorded thereon, and an elementactuated by said recorded wave, said element having a natural periodsubstantially equal to the frequency of the constant frequency componentof the wave on the record.

5. In combination, a phonograph record having a modulated wave recordedthereon and a reproducer comprising a piezo-electric crystal whosenatural period equals that of the recorded wave.

6. In combination, a record having a wave of modulated inaudiblefrequency recorded thereon, and a reproducer having an elementresponsive to said recordings and whose natural period equals that ofthe recorded inaudible wave.

7. In combination, a uniformly rotatable member having recordings ofmodulated constant frequency thereon, and an element responsive to saidrecordings whose natural period substantially equals that of therecordings.

8. In combination, a record having a wave of constant frequency recordedthereon, and a piezoelectric crystal whose natural period of vibrationequals that of the wave recorded on the record adapted to be actuated bysaid recorded wave.

9. In combination, an element having a wave of constant frequencyrecorded thereon, a piezo electric crystal whose natural period ofvibration equals that of the constant frequency wave recorded on theelement, and means for actuating said crystal by the constant frequencyrecordmg.

10. In combination, a movable element having recordings of asubstantially constant frequency thereon, a piezo electric crystal whosenatural period of vibration substantially equals that of the recording,and means adapted to be actuated by said recordings for mechanicallyvibrating said crystal.

JULIUS WEINBERGER.

